Abstract : Analytic combat models are abstract models that have received interest in the operations research community. These models are distinguished by the integration of basic combat events into an overall mathematical structure. Analyses of these models are performed by logically consistent mathematical transformations and deductions. Although analytic combat models may be either stochastic or deterministic, they are almost invariably driven by systems of ordinary differential equations. Almost all analytic combat models to date are based on Lanchester type equations or small modifications thereof. In order to embrace considerations of spatial distribution of forces the notion of combat unit densities is employed. (hereafter referred to as c.u. density). A derivation of the mathematical model will demonstrate a natural method for handling c.u. densities. The model is developed in Eulerian coordinates with each model component being in general a function of space and time.